Background: Patients with irritable bowel syndrome (IBS) have often attributed certain foods as common triggers for the worsening of gastrointestinal (GI) symptoms. However, the role of diet in the management of IBS symptoms has not clearly been established. Recently, the effect of fibre, gluten and FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols) on gastrointestinal symptoms have been investigated with conflicting results. Questionnaires are commonly used to collect information about participant’s symptoms, while the most accurate method to measure an individual’s dietary intake is a multiple-day food record. Despite this, there is surprisingly no validated food and symptom diary for IBS to investigate the role of diet upon IBS symptoms.

Objective: The aim of this pilot study is to investigate the relationship between the consumption of fibre, gluten, and FODMAPs and subsequent gastrointestinal symptoms in IBS participants to determine the predictive validity of the food and gastrointestinal symptom diary. This will be achieved by validating the real-time gastrointestinal symptom scales incorporated into a food and gastrointestinal symptom diary for IBS.

Methods: A three-day estimated food and real-time gastrointestinal symptom diary was completed by 51 participants with IBS, along with several legacy instruments. All food items consumed were entered for analysis into the food and nutrient analysis program; Kai-culator. To validate the real-time gastrointestinal symptoms, the relationship between the symptoms and the legacy instruments were examined using Spearman’s correlation coefficients. The legacy instruments used are the PROMIS (Patient Reported Outcome Measurement Information System) GI scales, the GSRS (Gastrointestinal Symptom Rating Scale), and the IBS-QOL (Irritable Bowel Syndrome Quality of Life). Further statistical analysis investigated the relationship between food intake and gastrointestinal symptoms.

Results: The real-time gastrointestinal symptom scales showed moderate correlations for the severity and length of time the symptoms were experienced with the PROMIS GI scales legacy instrument (0.31-0.64, p<0.05), and moderate correlations for the severity of the symptoms experienced with the GSRS legacy instrument (0.28-0.46, p<0.05), with the exception of the subscale constipation for both instruments. The IBS-QOL legacy instrument showed moderate correlations with the real-time gastrointestinal symptom abdominal bloating (0.33-0.39, p<0.05) only. Food intake did not differ significantly according to IBS subtype (fibre p=0.785, gluten p=0.270, and FODMAPs p=0.743). Higher FODMAP intake was associated with more severe abdominal bloating (p<0.05). Consuming lesser amounts of fibre was associated with more severe abdominal pain prior to a bowel motion, and with more severe straining to have the bowel motion (both p<0.05).

Conclusion: The novel real-time gastrointestinal symptom scales show reasonable reliability to measure gastrointestinal symptoms as they occur in IBS participants. Incorporated into a food and symptom diary, this enables a deeper understanding of the association between the consumption of specific food and nutrients and the generation of gastrointestinal symptoms, providing a valid instrument to increase the knowledge and options for the treatment of IBS symptoms.